Les rouilles vertes sont des hydroxysels mixtes Fe(II)-Fe(III) présents dans les sols hydromorphes sous forme de fougérite. Elles sont connues pour être capable de réduire des polluants organiques et métalliques. Les rouilles vertes peuvent être produites à partir de la bioréduction de lépidocrocite [gamma]-FeOOH par Shewanella putrefaciens, une bactérie ferriréductrice. En vue de comprendre leur formation dans l'environnement et d'utiliser leur réactivité dans la mise en place, à terme, d'un système de dépollution des sols et des eaux (colonne de sable), nous avons étudié leur formation dans un système en batch en présence d'une phase siliceuse (sable et acide silicique) et en présence de polymères organiques synthétiques (polyacrylate PAA et polyacrylamide PAM) afin de mimer la présence des corps bactériens. La silice est les polymères apparaissent comme de bons agents stabilisateurs, favorables à la formation des rouilles vertes. Les rouilles vertes formées en présence de ces agents stabilisateurs conservent leur capacité réductrice vis-à-vis d'un polluant organique, le rouge de méthyle et d'un polluant métallique, le mercure Hg2+. Nous avons ensuite transposé notre système en batch dans une colonne de sable + lépidocrocite [gamma]-FeOOH, soumise à un régime hydrodynamique. Nous avons réussi à former et à caractériser une rouille verte comme minéral secondaire de la bioréduction de la lépidocrocite par Shewanella putrefaciens / Green rusts are mixed species Fe(II)-Fe(III) present in hydromorphic soils as fougerite. They are capable to reduce organic and metallic pollutants. Green rusts may be produced from the bioreduction of lepidocrocite [gamma]-FeOOH by Shewanella putrefaciens, a dissimilatory iron reducing bacteria. In order to understand their formation routes in the environment and eventually, use their reactivity in a system for soil and water remediation (sand column), we studied their formation in a batch system with silica phase (quartz sand and silicic acid) and with two organic polymers (PAA polyacrylate and polyacrylamide PAM).The silica polymers appear to be good stabilizers, favorable to the formation of green rusts. Green rusts formed in the presence of the stabilizing agents retain their reductive capacity toward an organic pollutant, methyl red and a metallic pollutant, mercury Hg2+. Then, we have transposed our system in a flow through column of sand + lepidocrocite [gamma]-FeOOH. The carbonate green rust was formed and identified as secondary mineral of lepidocrocite bioreduction by Shewanella putrefaciens

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / O Brasil à o maior produtor mundial de laranja e de suco de laranja, sendo este setor de grande importÃncia para economia brasileira, responsÃvel por gerar mais de 400 mil empregos e movimentar cifras de bilhÃes de reais por ano. Mas, este setor tambÃm à responsÃvel pela produÃÃo de grande quantidade de rejeitos industriais, que equivalem a 50% do peso da fruta, sendo estes resÃduos utilizados na maioria das vezes como raÃÃo animal. Portanto o uso eficiente destes rejeitos se faz necessÃrio em um mundo em que as reservas naturais vÃm se esgotando. Neste sentido a biocatÃlise mostra-se como uma ferramenta promissora no uso destes resÃduos, que possuem enzimas em sua constituiÃÃo, para obtenÃÃo de produtos de alto valor agregado, as substÃncias enantiopuras. A aplicaÃÃo de diferentes metodologias, prÃticas e de baixo custo, possibilitou a sÃntese de alcoÃis quirais com alto excesso enantiomÃrico (ee) e boas taxas de conversÃo. ReaÃÃes de hidrÃlise e reduÃÃo foram processadas em meio aquoso e, as reaÃÃes de esterificaÃÃo foram realizadas em solvente orgÃnico, utilizando as casca da laranja como fonte de biocatalisadores. O uso das cascas da laranja como fonte de biocatalisador apresentou resultados bastante promissores, demonstrando capacidade catalÃtica em vÃrias reaÃÃes (reduÃÃo/oxidaÃÃo, hidrÃlise/esterificaÃÃo) atravÃs de metodologias simples e de baixo custo. ConversÃes de 46,90-96,70% foram alcanÃadas nas reaÃÃes de biorreduÃÃo acompanhado de ee variando de 21,15-99,00%. Nas reaÃÃes de hidrÃlise verificaram-se taxas de conversÃes de 19,20-80,82% e ee variando de 9,60-45,52%. Jà nas reaÃÃes de esterificaÃÃo, ee acima de 99% foram observados e conversÃes maiores que 80% foram alcanÃadas. Portanto, este estudo abre precedentes para uma ampla faixa de aplicaÃÃo desta fonte de biocatalisador (cascas da laranja), que atualmente à considerado como um rejeito industrial, contribuindo sobremaneira para agregar valor a todo um setor produtivo e industrial no qual o Brasil à lÃder, a indÃstria de suco de laranja. / The Brazil is the producing greater of world of orange and orange juice, being this sector of great importance for Brazilian, responsible economy for generating 400 thousand jobs and more than and putting into motion ciphers of billions per year. But, this sector also is responsible for the production of great amount of industrial rejetcs, that are equivalent 50% of the weight of the fruit, being these used residues most of the time as animal ration. Therefore the use efficient of these rejetcs if makes necessary in a world where the natural reserves come if depleting. In this direction biocatalysis is presented as a promising tool in the use of these residues, that contains enzymes in its constitution, for attainment of products of high added value, the substances enantiopure. The application of different methodologies, practical and of low cost, made possible the chiral alcohols synthesis with high enantiomeric excess (ee) and good taxes of conversion. Hydrolysis reactions and reduction had been processed in aqueous way e, the reactions of esterification had been carried through in organic solvent, using the rind of the orange as source of biocatalysis for such reactions. The use of the peel of the orange as biocatalysis source presented resulted sufficiently promising, demonstrating catalytic capacity in some reactions (reduction/oxidation, hydrolysis/esterification) through simple methodologies and of low cost. Conversions of 46,90-96,70% had been reached in the reactions of bioreduction shown of ee varying of 21,15-99,00%. In the hydrolysis reactions taxes of 19,20-80,82% conversions and ee had been verified varying of 9,60-45,52%. Already in the esterification reactions, ee above of 99% had been observed and bigger conversions that 80% had been reached. From there, this study it opens precedents for an ample band of application of this source of biocatalysis (pells of the orange), that currently it is considered as one reject industrial, contributing excessively to add value all a productive and industrial sector in which Brazil is leader, the orange juice industry

Submitted by MILENA NOVA CASTELBLANCO null (milenan80@gmail.com) on 2016-05-18T23:09:22Z No. of bitstreams: 1 Dissertação_Biotecnologia_Milena_Nova.pdf: 2319209 bytes, checksum: 5f8a2cf09d53469b118673ce803f4c05 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-05-20T19:50:02Z (GMT) No. of bitstreams: 1 castelblanco_mn_me_araiq_par.pdf: 1007182 bytes, checksum: a277306214e78520e7169816799bf058 (MD5) / Made available in DSpace on 2016-05-20T19:50:02Z (GMT). No. of bitstreams: 1 castelblanco_mn_me_araiq_par.pdf: 1007182 bytes, checksum: a277306214e78520e7169816799bf058 (MD5) Previous issue date: 2016-05-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A demanda crescente de metais como ferro, cobre, entre outros ocasionou o esgotamento progressivo dos depósitos minerais; de tal modo que as companhias mineradoras desenvolveram tecnologias alternativas aos métodos convencionalmente aplicados para a recuperação e extração de metais valiosos partir de minerais de baixo teor e outras fontes de metais polimetálicos como minerais de ferro que contem metais de base associados. Uma dessas alternativas é a biomineração que utiliza principalmente microrganismos procariontes e eucariontes para acelerar a dissolução oxidativa de minerais sulfetados presentes em minérios de baixo teor produzindo a solubilização de metais associados; esta biotecnologia é atualmente usada apenas para processar minérios reduzidos e rejeitos minerais uma vez que a maioria destes minerais são sulfetados. No entanto, muitos metais de valor econômico também são encontrados em minerais que são parcial ou totalmente oxidados como as lateritas de cobre ou níquel, minerais que não são susceptíveis à dissolução oxidativa; portanto, os minerais de ferro férrico contidos nesses minérios não podem ser processados oxidativamente, pois estes compostos são susceptíveis de serem reduzidos por processos biológicos, derivando na solubilização de metais associados. Microrganismos acidófilos tais como Acidithiobacillus ferrooxidans podem catalisar a redução dissimilatória de íons férricos na ausência de oxigênio para acelerar a solubilização destes metais. Estudos recentes têm mostrado que essa nova abordagem pode ser utilizada para extrair metais tais como níquel e cobre a partir de minérios oxidados a uma velocidade mais elevada do que pode ser conseguido por processos oxidativos. Neste trabalho, foram realizados ensaios de redução biológica de íons férricos acoplado a oxidação anaeróbia de enxofre elementar em um biorreator automatizado de 2 L com temperatura, agitação e pH constantes, usando um minério de ferro e uma cultura pura da bactéria anaeróbia facultativa At. ferrooxidans. A amostra foi fornecida pelo Instituto Tecnológico Vale - Desenvolvimento Sustentável (ITV-DS) e analisada por difração de raios X (DRX) evidenciando fases dominantes de monazita (Ce, La, Nd, Th) PO4, coesita (SiO2) e goethita (FeO (OH)). Os resultados do processo mostraram que metais como Cr, Al, Ca, Co Cu, K, Mg Mn, Ni, Pb e Zn foram solubilizados no processo bioredutivo com porcentagens de remoção de 93,3% para Mn e 34,7 para Zn, Nb um metal raro e as terras raras como lantânio (La) e cério (Ce) foram também solubilizadas no processo com 61%,17,9 % e 3,2% respetivamente, as outras terras raras que não solubilizaram como Sm e Nd foram expostas no resíduo mineral. Também foram solubilizados fosfatos nos primeiros dez dias atingindo 1% de solubilização. O resíduo solido foi avaliado por DRX e apresentou formação de novas fases como sodalita (K7,7Na0,3(AlSiO4)6(Cl)4)2), berlinita (AlPO4) e hematolita ((Mn2+, Mg, Al)15(AsO3) (AlO4)2(OH)2) e uma aparente diminuição da presença das fases de goethita e monazita. A análise do resíduo por microscopia eletrônica de varredura com emissão de campo (MEV-FEG) mostrou uma diferença na diminuição da presença das partículas menores presentes na amostra original e claramente uma maior presença de partículas maiores no sólido biolixiviado. Os resultados obtidos neste trabalho mostraram a recuperação de diversos metais, além de terras raras num minério de ferro, a recuperação de fosfatos que não estava prevista como objetivo inicial do trabalho, também foi observada. Estes resultados evidenciam que a dissolução redutiva catalisada por bactérias é uma alternativa promissória para a utilização de diversos tipos de minério de baixo teor que não poderiam ser processados por processos oxidativos e que seriam uma fonte para a recuperação de metais e outros compostos de interesse econômico, além de ser. ambientalmente amigável comparada com os processos convencionalmente aplicados para a recuperação de metais. / The growing demand for metals such as iron, copper, and others has caused the gradual exhaustion of mineral deposits; such a way that the mining companies have developed technologies alternative to the methods conventionally applied for the recovery and extraction of valuable metals from low grade minerals and other sources of polymetallic metals such as iron minerals which contains base metals associated. One such alternative is the biomining which uses mainly microorganisms prokaryotes and eukaryotes to accelerate the oxidative dissolution of sulphide minerals present in low grade ores producing solubilization of associated metals; This biotechnology is currently used only to process reduced ores and minerals tailings since most of these minerals are sulphides. However, many metals of economic value are also found in minerals that are partially or fully oxidized like copper or nickel laterites, minerals that are not susceptible to oxidative dissolution; therefore, the mineral ferric iron contained in these ores can not be oxidatively processed, since these compounds are capable of being reduced by biological processes, deriving the associated solubilizing metals. Acidophilic microorganisms such as Acidithiobacillus ferrooxidans can catalyze the dissimilatory reduction of ferric iron in the absence of oxygen to accelerate the solubilization of these metals. Recent studies have shown that this new approach can be used to extract metals such as copper and nickel from oxide ores at a higher speed than can be achieved by oxidative processes. In this work were carried out biological reduction tests of ferric iron coupled anaerobic oxidation of elemental sulfur in an automated bioreactor 2 L with temperature, agitation and pH constant in anaerobic conditions using an iron ore and a pure culture of facultative anaerobic bacterium At. ferrooxidans. The sample was provided by the Vale Technology Institute - Sustainable Development (ITV-DS) and analyzed by X-ray diffraction (XRD) showing dominant phases of monazite ((Ce, La, Nd, Th) PO4), coesita (SiO2) and goethite (FeO (OH)). The process results showed that metals such as Cr, Al, Ca, Co Cu, K, Mg, Mn, Ni, Pb and Zn were solubilized in the bioreductive process with removal percentages 93.3% by Mn and 34.7, for Zn, Nb, a rare metal and rare earths elements such as lanthanum (La) and cerium (Ce) were also solubilized in the process with 61%, 17.9% and 3,2% respectively, other rare earths not solubilized as Sm and Nd were exposed in the mineral residue. Also were solubilized phosphates in the first ten days to reach 1% solubilization. The solid residue was evaluated by XRD and showed formation of new phases such as sodalite (K7,7Na0,3(AlSiO4)6(Cl)4)2), berlinita (AlPO4) and hematolita ((Mn2+, Mg, Al)15(AsO3) (AlO4)2(OH)2) and an apparent reduction in the presence of goethite and monazite phases Analysis of the residue by scanning electron microscopy with field emission (SEM-FEG) showed a difference in reducing the presence of smaller particles present in the original sample and clearly a greater presence of larger particles in the solid biolixiviado. The results of this study showed the recovery of various metals, besides rare earths in an iron ore, phosphates recovery which was not expected as initial objective of this study was also observed. These results show that the reductive dissolution catalyzed by bacteria is a promising alternative to the use of different types of low grade ores that could be processed by oxidative processes and it would be a source for recovery of metals and other compounds of economic interest, besides being environmentally friendly compared to the processes conventionally applied to the recovery of metals.

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / O estudo da biocatÃlise tem se intensificado nos Ãltimos anos devido à busca de rotas sintÃticas alternativas para a obtenÃÃo de compostos enantiomericamente puros. A utilizaÃÃo de sementes de Helianthus annuus L. ainda nÃo foi relatada na literatura em reaÃÃes de biorreduÃÃo e diante dessa perspectiva, foram investigadas na biorreduÃÃo de cetonas aromÃticas, para a obtenÃÃo de Ãlcoois enantiomericamente puros. O teor de proteÃnas das sementes foi determinado pelos mÃtodos de Lowry e Bradford e apresentaram valores correspondentes a 10,1 g/L e 8,8 g/L, respectivamente. As reaÃÃes de biorreduÃÃo foram otimizadas utilizando acetofenona (1), e nestas foram avaliados os fatores: quantidade de biocatalisador, meio tamponante (pH), co-solvente, germinaÃÃo de sementes e extrato bruto com polivilpirrolidona (PVP). Foram obtidos boas conversÃes (56,9%) em meio aquoso e, excelentes excessos enantiÃmericos (ee), (>99,0%) com o extrato bruto enzimÃtico em PVP do enantiÃmero (S). Derivados da acetofenona, uma cetona α-halogenada e duas outras cetonas aromÃticas, α-tetralona e α-indanona, foram submetidas Ãs metodologias otimizadas de conversÃo e ee, obtendo-se bons resultados, com produÃÃo do enantiÃmero S, exceto para a 3-metÃxi-acetofenona em meio aquoso, que apresentou o isÃmero R. A quantificaÃÃo dos teores de conversÃo foi realizada por intermÃdio da construÃÃo de curvas de calibraÃÃo em CromatogrÃfo LÃquido de Alta EficiÃncia (CLAE), bem como a resoluÃÃo dos Ãlcoois quirais utilizando coluna quiral OB-H. / The study of biocatalysis has intensified in recent years due to the search for alternative synthetic routes to obtain enantiomerically pure compounds. The use of seeds of Helianthus annuus L. has not been reported in the literature and bioreduction reactions at this point of view, were investigated in the bioreduction of aromatic ketones, to obtain enantiomerically pure alcohols. The protein content of the seeds was determined by Lowry and Bradford methods and gave values corresponding to 10,1g/L and 8,8g/L, respectively. The bioreduction reactions were optimized using acetophenone (1), and these factors were evaluated: the amount of biocatalyst, using buffer (pH), co-solvent, seed germination and the crude extract with polyvinylpyrrolidone (PVP). Good conversions were obtained (56,9%) in aqueous solution and excellent enantiomeric excess (ee) (>99,0%) crude extract with the enzyme in PVP enantiomer (S). Derivatives of acetophenone, an α-halogenated ketone and two other aromatic ketones, α-tetralone and α-indanone were subjected to the methods of conversion and ee optimized to yield good results, with production of the S enantiomer, except for the 3-methoxy-acetophenone in aqueous media, which made the R isomer. Quantitation of the conversion levels were determined by the construction of calibration curves in a High Efficiency Liquid Chromatograph (HPLC) and the resolution of chiral alcohols using a chiral column OB-H.

Submitted by Biblioteca da Faculdade de Farmácia (bff@ndc.uff.br) on 2017-04-19T17:50:00Z No. of bitstreams: 1 Oliveira, Simone Santos de Sousa [Dissertação, 2012].pdf: 991123 bytes, checksum: 0920cf1854462d2adaacf1b65b31e369 (MD5) / Made available in DSpace on 2017-04-19T17:50:00Z (GMT). No. of bitstreams: 1 Oliveira, Simone Santos de Sousa [Dissertação, 2012].pdf: 991123 bytes, checksum: 0920cf1854462d2adaacf1b65b31e369 (MD5) / Os beta-hidroxiésteres são importantes intermediários para a síntese de substâncias bioativas e outros produtos de interesse econômico. A forma de obtenção mais vantajosa, atualmente, é a redução microbiana (biorredução) de beta-cetoésteres. Esse tipo de processo possibilita produzir alto excesso enantiomérico do isômero desejado, ao contrário da síntese química convencional que, geralmente, produz misturas racêmicas. A maioria das reduções microbianas resulta em excesso do enantiômero (S), mas também é observada a inversão dessa configuração, dependendo da estrutura do substrato e do microrganismo utilizado. No presente trabalho, -hidroxiésteres quirais foram obtidos a partir da biorredução enantiosseletiva de oito beta-cetoésteres: 3-oxobutanoato de etila (1), 3-oxopentanoato de metila (3), 3-oxopentanoato de etila (4), 3-oxohexanoato de etila (5), 4-cloro-3-oxobutanoato de metila (7), 4,4,4-tricloro-3-oxobutanoato de etila (8), 4,4,4-triflúor-3-oxobutanoato de etila (9) e 3-(4-clorofenil)-3-oxopropanoato de metila (11), utilizando a levedura Kluyveromyces marxianus como biocatalisador. Esta levedura apresentou altíssima enantiosseletividade (R), com excesso enantiomérico de aproximadamente 100% na redução dos β-cetoésteres 3, 4 e 5. Com o propósito de obter padrões para a caracterização dos produtos da reação microbiológica, visto que não há no mercado a disponibilidade de padrões para todos os betahidroxiésteres obtidos neste estudo, estes foram sintetizados por redução química aquiral com boroidreto de sódio, em dois diferentes meios reacionais, metanol e glicerol. A redução química em glicerol apresentou melhores resultados do que a metodologia convencional com metanol. Técnicas de modelagem molecular foram utilizadas para uma correlação entre as estruturas dos beta-cetoésteres e os resultados de conversão e excesso enantiomérico obtidos nos experimentos de biorredução. O mapa de LUMO foi o melhor parâmetro para esta correlação / The β-hydroxyesters are important intermediates for the synthesis of bioactive substances and other products of economic interest. The most advantageous way to obtain the microbial reduction (bioreduction) is currently β-ketoesters. Such process allows to produce high enantiomeric excess of the desired isomer, unlike the conventional chemical synthesis, which generally produces racemic mixtures. Most microbial reduction result in enantiomeric excess of the enantiomer (S), but it was observed the reversal of this configuration, depending on the structure of the substrate and the microorganisms used. In the present study β-hydroxyesters chiral were obtained from the enantioselective bioreduction of eight β-ketoesters: ethyl 3-oxobutanoate (1), methyl 3-oxopentanoate (3), ethyl 3-oxopentanoate (4), ethyl 3-oxohexanoate (5), methyl 4-chloro-3-oxobutanoate (7), ethyl 4,4,4-trichloro-3-oxobutanoate (8), ethyl 4,4,4-trifluoro-3-oxobutanoate (9) and methyl 3-(4-chlorophenyl)-3-oxopropanoate (11), using the yeast Kluyveromyces marxianus as biocatalyst. This yeast showed high enantioselectivity R, with enantiomeric excess of about 100% reduction of β-ketoesters 3, 4 and 5. In order to synthesize the standards for the characterization of the products after the reaction microbiological, since there are no market standards for the availability of all β- hydroxyesters of this study, we used achiral chemical reduction with sodium borohydride in two different reaction media, methanol and glycerol. The chemical reduction in glycerol showed better results than the conventional method with methanol. Molecular modeling techniques were used for a correlation between the structures of β-ketoesters and the results of conversion and enantiomeric excess obtained in the bioreduction experiments. The map of LUMO was the best parameter for this correlation

Submitted by Carolina Neves (carolinapon@uefs.br) on 2017-02-17T23:59:52Z No. of bitstreams: 1 Disserta??oJoseneideAlves.pdf: 3612959 bytes, checksum: a4ba8033510286e66a0d4453ad52d71d (MD5) / Made available in DSpace on 2017-02-17T23:59:53Z (GMT). No. of bitstreams: 1 Disserta??oJoseneideAlves.pdf: 3612959 bytes, checksum: a4ba8033510286e66a0d4453ad52d71d (MD5) Previous issue date: 2009-08-31 / The biorreduction has great importance in the production of optically pure substances and is widely used for asymmetric synthesis. Bioconversions occur with high specificity and efficiency because they are catalyzed by enzymes, forming one of the isomers from a pro-chiral substrate. This work had as main objective to evaluate the potential reduction of micro-organisms (yeasts, bacteria and fungi) isolated in the state of Bahia using as carbonyl substrate the acetophenone, analyzing its conversion into alcohol and identifying the enantiomeric excess produced. Strains of Saccharomyces cerevisiae isolated from sugar cane brandy distilleries of Bahia state, rhizobacteria isolated from Arachis pintoi (forage peanut) in southern Bahia and endophytic fungi isolated Hevea brasiliensis. The products were analyzed by gas chromatography coupled to mass spectrometry to verify the conversion of the substrate in alcohol and enantiomeric excess was determined by gas chromatography with chiral stationary phase. Of the 28 microorganisms evaluated 18 acted as biocatalysts. Products of reduction of acetophenone were obtained with yields between 6 and 79% and enantiomeric excess from 41 to 100%. Fungi CDC026, CDC086 and MDF077 converted acetophenone into (R)-alcohol, with ee of 54, 56, and 84%, while the other strains that showed positive results for acetophenone yielded the (S)-alcohol. Whereas 64% of test organisms were able to act as catalysts in the enantioseletive reduction of acetophenone, it was observed that the microbial diversity of the state of Bahia is a source of new catalysts for the production of enantiomeric pure compounds. / A Biorredu??o tem grande import?ncia na produ??o de subst?ncias opticamente puras, sendo amplamente utilizada para s?nteses assim?tricas. As bioconvers?es ocorrem com alta especificidade e efici?ncia por serem catalisadas por enzimas, formando um dos is?meros a partir de um substrato pr?-quiral. O presente trabalho teve como objetivo principal avaliar o potencial redutor dos microrganismos (leveduras, bact?rias e fungos) isolados no territ?rio baiano frente ao substrato carbon?lico acetofenona; verificando a convers?o do substrato (acetofenona) em ?lcool quiral e identificando o excesso enantiom?rico com que as rea??es biocatal?ticas ocorreram. Foram utilizadas culturas de Saccharomyces cerevisiae isoladas em cacha?arias do estado da Bahia, rizobact?rias isoladas no sul da Bahia e fungos endof?ticos. Foi testada a a??o desses microrganismos sobre o substrato acetofenona. Os produtos foram analisados por Cromatografia gasosa acoplada a espetrometria de massa, para verificar a convers?o do substrato em ?lcool; o excesso enantiom?rico foi obtido em cromat?grafo gasoso equipado com coluna quiral obtendo-se separa??o para os is?meros da acetofenona com um excesso enantiom?rico de at? 100%, para a cepa bacteriana I68. Os fungos CDC026 e CDC086 converteram a acetofenona em (R)-?lcool, as demais cepas que apresentaram resultados positivos para aceofenona produziram o (S)-?lcool em excesso. Conclui-se que em geral os microrganismos testados apresentaram boa capacidade de redu??o da acetofenona em experimentos de biotransforma??o, constituindo-se fontes de compostos enantiomericamente puros.

Sulfate-reducing bacteria (SRB) frequently occur in the deep granitic rock aquifers at the Äspö Hard Rock Laboratory (Äspö HRL), Sweden. The new SRB strain Desulfovibrio äspöensis could be iso-lated. The objective of this project was to explore the basic interaction mechanisms of uranium, curium, neptunium and plutonium with cells of D. äspöensis DSM 10631T. The cells of D. äspöensis were successfully cultivated under anaerobic conditions as well in an optimized bicarbonate-buffered mineral medium as on solid medium at 22 °C. To study the interaction of D. äspöensis with the actinides, the cells were grown to the mid-exponential phase (four days). The collected biomass was usually 1.0±0.2 gdry weight/L. The purity of the used bacterial cultures was verified using microscopic techniques and by applying the Amplified Ribosomal DNA Restriction Enzyme Analysis (ARDREA). The interaction experiments with the actinides showed that the cells are able to remove all four actinides from the surrounding solution. The amount of removed actinide and the interaction mechanism varied among the different actinides. The main U(VI) removal occurred after the first 24 h. The contact time, pH and [U(VI)]initial influence the U removal efficiency. The presence of uranium caused a damaging of the cell membranes. TEM revealed an accumulation of U inside the bacterial cell. D. äspöensis are able to form U(IV). A complex interaction mechanism takes place consisting of biosorption, bioreduction and bioaccumulation. Neptunium interacts in a similar way. The experimental findings are indicating a stronger interaction with uranium compared to neptunium. The results obtained with 242Pu indicate the ability of the cells of D. äspöensis to accumulate and to reduce Pu(VI) from a solution containing Pu(VI) and Pu(IV)-polymers. In the case of curium at a much lower metal concentration of 3x10-7 M, a pure biosorption of Cm(III) on the cell envelope forming an inner-sphere surface complex most likely with organic phosphate groups was detected. To summarize, the strength of the interaction of D. äspöensis with the selected actinides at pH 5 and actinide concentrations ≥10 mg/L ([Cm] 0.07 mg/L) follows the pattern: Cm > U > Pu >> Np.

Magister Scientiae - MSc (Physics) / Zinc oxide (ZnO) is a wide and direct semiconductor with a wurtzite crystal structure. Its multifunctionality as the ideal candidate in applications such as blue-UV light emitting diodes, transparent conducting oxide, selective gas sensor and efficient catalyst support among others, has attracted a significant interest worldwide. Nano-scaled ZnO has been synthesized in a plethora of shapes. A rich variety of physical and chemical methodologies have been used in the synthesis of undoped or doped ZnO. However, such methods either necessitate relatively high vacuum infrastructures, elevated temperatures, or the use of toxic reagents. The "green chemistry" synthesis of metal oxide nanoparticles which is based on using natural plant extract as an effective 'reducing agent' of metal precursor, has been reported to be a cleaner and environment-friendly alternative to the physical and chemical methods. The thesis is based on the synthesis and the main physical properties of pure ZnO nanoparticles synthesized by a completely green chemistry process using the natural extract of Aspalathus Linearis to bio-reduce the zinc acetate precursor. The obtained ZnO nanopowdered samples were annealed at different temperatures from 300 °C to 600 °C. The samples were characterized using Scanning Electron Microscopy, Energy Dispersive Spectroscopy, Transmission Electron Microscopy, X-ray Diffraction, Differential Scanning Calorimetry, Thermogravimetric Analysis and Fourier Transform Infrared. Highly pure quasi-spherical ZnO nanoparticles with an average crystallite size of 24.6 nm (at 300 °C), 27.2 nm (at 400 °C), 27.6 nm (at 500 °C), and 28.5 nm (at 600 °C) were found. The results also showed that the average crystallite size increased with an increase in annealing temperature. It was successfully demonstrated that the natural plant extract of Aspalathus Linearis can be used in the bio-reduction of zinc acetate dihydrate to prepare highly pure ZnO nanoparticles.

Sulfate-reducing bacteria (SRB) frequently occur in the deep granitic rock aquifers at the Äspö Hard Rock Laboratory (Äspö HRL), Sweden. The new SRB strain Desulfovibrio äspöensis could be iso-lated. The objective of this project was to explore the basic interaction mechanisms of uranium, curium, neptunium and plutonium with cells of D. äspöensis DSM 10631T. The cells of D. äspöensis were successfully cultivated under anaerobic conditions as well in an optimized bicarbonate-buffered mineral medium as on solid medium at 22 °C. To study the interaction of D. äspöensis with the actinides, the cells were grown to the mid-exponential phase (four days). The collected biomass was usually 1.0±0.2 gdry weight/L. The purity of the used bacterial cultures was verified using microscopic techniques and by applying the Amplified Ribosomal DNA Restriction Enzyme Analysis (ARDREA). The interaction experiments with the actinides showed that the cells are able to remove all four actinides from the surrounding solution. The amount of removed actinide and the interaction mechanism varied among the different actinides. The main U(VI) removal occurred after the first 24 h. The contact time, pH and [U(VI)]initial influence the U removal efficiency. The presence of uranium caused a damaging of the cell membranes. TEM revealed an accumulation of U inside the bacterial cell. D. äspöensis are able to form U(IV). A complex interaction mechanism takes place consisting of biosorption, bioreduction and bioaccumulation. Neptunium interacts in a similar way. The experimental findings are indicating a stronger interaction with uranium compared to neptunium. The results obtained with 242Pu indicate the ability of the cells of D. äspöensis to accumulate and to reduce Pu(VI) from a solution containing Pu(VI) and Pu(IV)-polymers. In the case of curium at a much lower metal concentration of 3x10-7 M, a pure biosorption of Cm(III) on the cell envelope forming an inner-sphere surface complex most likely with organic phosphate groups was detected. To summarize, the strength of the interaction of D. äspöensis with the selected actinides at pH 5 and actinide concentrations ≥10 mg/L ([Cm] 0.07 mg/L) follows the pattern: Cm > U > Pu >> Np.

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